Hi Paul - I'd love to say "great minds think alike." <img src="images/graemlins/grin.gif" alt="" />
I've been carrying the same thing for about a year. I add a bandanna stuffed into the cup, under the bottle, with a very small corner peeking out above the lip of the cup so I can get it out - it wedges the bottle into the cup very tightly.
I recently got a small shoulder bag instead of my too-big daypack, and I then had to get a small pouch that I can attach to the shoulder bag to hold the bottle.
I'm less likely to need to cook in a daily commute/walk, but I like having that as a possibility. Mainly, I think of it as a way to share the water if, for instance, I'm stuck on a subway train for quite a while and someone needs a drink - I can control how much they get, and we're not all drinking out of the same bottle...and if someone doesn't give it back, I've still got the water.
Dave